Abstract

A testing instrument for camera lenses is described which automatically measures transfer functions and line spread functions provided the focusing plane is maintained. The frequency covers a continuous range of 0 lines/mm to 150 lines/mm. The gauging to 1 with 0 lines/mm of the transfer function is automatic under all f stop, color, and defocusing conditions. The misalignment caused by instrumentation and the measuring principle is compensated by a function potentiometer. The instrument described allows focusing to infinity by collimators and focusing up to 6 m without collimators. Evaluated and measured curves are compared.

© 1968 Optical Society of America

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References

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  1. G. Franke, Optik 18, 220 (1961).
  2. M. Born, R. Furth, R. W. Pringle, Phil. Mag. 31, 1 (1946).
  3. K. G. Birch, Dissertation, 1958.
  4. H. H. Hopkins, Proc. Phys. Soc. 79, 889 (1962).
    [CrossRef]
  5. H. Wasmund, Diplomarbeit, Marburg (1966).

1962 (1)

H. H. Hopkins, Proc. Phys. Soc. 79, 889 (1962).
[CrossRef]

1961 (1)

G. Franke, Optik 18, 220 (1961).

1946 (1)

M. Born, R. Furth, R. W. Pringle, Phil. Mag. 31, 1 (1946).

Birch, K. G.

K. G. Birch, Dissertation, 1958.

Born, M.

M. Born, R. Furth, R. W. Pringle, Phil. Mag. 31, 1 (1946).

Franke, G.

G. Franke, Optik 18, 220 (1961).

Furth, R.

M. Born, R. Furth, R. W. Pringle, Phil. Mag. 31, 1 (1946).

Hopkins, H. H.

H. H. Hopkins, Proc. Phys. Soc. 79, 889 (1962).
[CrossRef]

Pringle, R. W.

M. Born, R. Furth, R. W. Pringle, Phil. Mag. 31, 1 (1946).

Wasmund, H.

H. Wasmund, Diplomarbeit, Marburg (1966).

Optik (1)

G. Franke, Optik 18, 220 (1961).

Phil. Mag. (1)

M. Born, R. Furth, R. W. Pringle, Phil. Mag. 31, 1 (1946).

Proc. Phys. Soc. (1)

H. H. Hopkins, Proc. Phys. Soc. 79, 889 (1962).
[CrossRef]

Other (2)

H. Wasmund, Diplomarbeit, Marburg (1966).

K. G. Birch, Dissertation, 1958.

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Figures (12)

Fig. 1
Fig. 1

Schematic diagram of measurement principle.

Fig. 2
Fig. 2

Realization of the spatial frequency N with a rotatable selection slit. The number of grating elements per length of the selection slit varies continuously with angle α.

Fig. 3
Fig. 3

Block diagram of electronics.

Fig. 4
Fig. 4

Correction function K1(α).

Fig. 5
Fig. 5

Correction function K2(α).

Fig. 6
Fig. 6

Correction function K(α) = K1(α) × K2(α).

Fig. 7
Fig. 7

Schematic of the optical path of the measuring instrument. Above: side view, below: upper view. HS—concave mirror, LW—lamp filament, K—condenser, W—heat filter, F—interference filter, B—stop, P1—Abbe-König prism, F1—field lens, S—object slit, O—collimator lens, KOL—collimator, SS—rotating mirror, PR—test lens, MO—microobjective, P2—Abbé-König prism, OKP—eyepiece prism, FL1—field lens 1, OK –eyepiece, DP—triangle prism (the leading edge is grounded to a slit), P3—Abbé-König prism, L—achromat, WP—prism system, SEV—photomultiplier, T—drum (is coated with the grating), FL2—field lens 2, Sch—photometer slit, WB—alternating stop, and P90°—90°prism.

Fig. 8
Fig. 8

Total view. Shown on the optical bench from left to right are lamphouse with object slit, lens turret with different collimator lenses (to pan out of the optical path by measurement for final object distance), rotating mirror, lens mounting with test lens and gauging head; in front the operator table with X-Y recorder.

Fig. 9
Fig. 9

Lamphouse with adjustable object slit. Different interference filters are inserted in the opening of the lamphouse. Scales for adjusting the azimuths of the object slit and of the Abbe-König prism 1 are fastened on the cylindrical nozzle.

Fig. 10
Fig. 10

Lens mounting with test lens, gauging head, and operator table with two-component recording instrument.

Fig. 11
Fig. 11

Comparison of computed and measured transfer functions of a lens almost free from geometrical aberrations at different stops.

Fig. 12
Fig. 12

Comparison of directly measured transfer functions and transfer functions obtained by Fourier transformation of measured line spread functions.

Equations (6)

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N = N 0 sin α .
U ( α , t ) = u 0 + n = 1 u n T ( n N sin α ) K ( α ) × cos [ ( 2 π n N v t - φ ( n N sin α ) ] ,
U 1 ( α , t ) = u 1 T ( N sin α ) K ( α ) cos [ 2 π N v t - φ ( N sin α ) ]
K 1 ( α ) = π b N 0 sin α sin ( π b N 0 sin α ) .
K 2 ( α ) = cos α sin ( π N 0 h ) sin ( π N 0 h cos α ) .
K ( α ) = K 1 ( α ) K 2 ( α ) .

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